Electronics > Repair
BK Precision 2120 trace issues
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bdunham7:
What do you mean by 'no current'??  There should have been a voltage reading of some sort on each.

The D502 reading is as expected--about a half a volt forward drop.  R504 and R505 are close enough to not worry about yet.  The others you probably have selected the wrong resistance range on your meter.  100K means 100,000 ohms, 47K means 47,000 ohms, 4K7 means 4,700 ohms, etc.  100KF means 100,000 ohms with a 1% tolerance.
vexatag:
By "no current" I mean I measured 0 volts of current. As for the resistors, I selected the continuity tester after failing to get any resistance in any range. As far as my meter could tell, the resistors are open.
bdunham7:
OK.  Just say 'volts' not 'volts of current' because the latter gives me visions of sparks flying due to putting the test leads in the wrong jacks on your meter. 

You need to check your meter.  Given what we have so far, I don't think you would have zero volts there.  Just to be clear, one lead on TP+140V test point, the other on one side or the other of R504?  Try putting that second lead to ground and verify you get 140 volts again.  And add in a third measurement from TP+140V to the lower side of D502 (or both sides if isn't clear which is which.

As for the resistors, it seems unlikely that they would all be open, user error or a malfunction your meter is more likely.  So try measuring some resistors in the 140V supply , lke R516, R517, etc.  Since we know that supply works, the resistors will probably be OK.

vexatag:
TP+140v to the chassis gets 140v, TP+140v to either side of R504 gets a 1 on the far left of my multimeter's display no matter what range I'm on. All of this is measured in DC. In AC mode some sporadic measurements happen but nothing more substantial than random noise. I connected in continuity mode very briefly but I started hearing a rapid clicking so I shut it down. TP+104 to the negative side of D502 got nothing, the positive side got 102v. After checking a couple known-good resistors on another PCB I have (little 1khz signal generator kit I have), I admit that I'm probably measuring them wrong.
bdunham7:
OK, there's still work to do.

First, please only use the DC 1000V or AC 750 volt ranges when doing power-on measurements on the oscilloscope--and definitely never ohms or continuity.  There's no need for any resolution better than 1 volt at this point.  The '1' on the left side may indicate overrange, meaning the voltage has exceeded the range.  If this happened on the 1000V range, there's something very wrong, hopefully with your meter because I have no idea where 1000V could come from.  Do you have a 9 volt battery or some other low voltage source handy?  Try setting your meter on 2V DC and giving it 9 volts (it won't hurt it) just to see if that '1' does indicate overrange.  And does your meter should indicate zero when there's no voltage, so when you measured from TP+140V to both sides of D502, you said it was 102V on one side and 'nothing' on the other.  If that 'nothing' was a zero reading that's  lot different than an overrange reading.

Do figure out how to get the ohms function working and verify it.  Getting your test instruments to work properly is all part of the struggle!

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